Tractor brake systems may include linkages between the left and right brake pedals and the left and right wheel brakes respectively. The linkages allow the left brake pedal to apply the left wheel brake, and the right brake pedal to apply the right wheel brake. One such linkage may be a hydraulic linkage which may include hoses, couplings and seals between each brake pedal and brake. Hydraulic brake linkages are costly to manufacture and assemble, and the seals and other components may deteriorate after extended use.
Mechanical linkages have been used between the left and right brake pedals and brakes. Mechanical linkages for a tractor brake system may be substantially lower in cost than hydraulic linkages. If a mechanical linkage includes a brake shaft that extends laterally across the vehicle, it may be necessary for the brake shaft to extend through an opening in the engine compartment or firewall. Openings in the engine compartment or firewall may compromise their effectiveness to block and shield the tractor cab from engine noise, as well as high engine temperatures, dirt and engine fumes.
A tractor brake system may include brake pedals for each of the left and right wheel brakes, a brake shaft extending laterally across the tractor, and mechanical linkages to each of the brakes. Openings for the brake shaft through the wall of an engine compartment or firewall may allow engine noise, as well as heat, dirt and fumes from the engine to enter the tractor cab area. It is desirable to improve the tractor cab working environment by minimizing engine noise from the engine to the cab, and reducing heat, dirt and fumes that may be transmitted from the engine to the cab.
In the past, sealing assemblies and bearings have been used to fit around components extending through openings in engine compartments or firewalls. For example, U.S. Pat. No. 3,844,374 relates to a seal assembly with three main elements arranged axially on a control link: a relatively thick washer-like member, a substantially hemispherical seal member, and a compression coil spring. U.S. Pat. Nos. 4,283,965 and 4,351,198 relate to sound attenuating bearings constructed of bushings fitted to the shaft of a hand and foot throttle control extending through the firewall. U.S. Pat. No. 4,033,425 relates to a mounting assembly which includes a grommet which has an annular groove and a central opening which supports a bearing element.
Prior art sealing devices and bearings are not effective to reduce or minimize engine noise, or to reduce heat, dirt and fumes passing through a gap around a brake shaft that extends through an engine compartment or firewall. Seals that are held against an engine compartment or firewall by clamps or springs may have a limited life and consume excessive space that is very limited within an engine compartment. Sound attenuating bearings are costly and require precise positioning and close dimensional tolerances within openings in an engine compartment or firewall. Bearings also may limit the lateral movement and/or rotation of a brake shaft within the opening. Rubber grommets may not provide a sufficiently strong seal to seal the gap between a brake shaft and opening in an engine compartment or firewall. An improved device is needed for minimizing engine noise, and reducing heat, dirt and fumes passing from an engine, around a brake shaft extending through the engine compartment or firewall, into a tractor cab.